Tutorial by Examples: d

URL url = new URL("http://example.com"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); try { BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream())); // read the input stream // in this case, I simply read t...

URL url = new URL("http://example.com"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); try { BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream())); // use a string builder to bufferize the response body //...

SQL injection is a kind of attack that allows a malicious user to modify the SQL query, adding unwanted commands to it. For example, the following code is vulnerable: // Do not use this vulnerable code! $sql = 'SELECT name, email, user_level FROM users WHERE userID = ' . $_GET['user']; $conn->...

The return type of a method can depend on the type of the parameter. In this example, x is the parameter, A is the type of x, which is known as the type parameter. def f[A](x: A): A = x f(1) // 1 f("two") // "two" f[Float](3) // 3.0F Scala will use type infe...

// Create a block with an asynchronous action var block = new ActionBlock<string>(async hostName => { IPAddress[] ipAddresses = await Dns.GetHostAddressesAsync(hostName); Console.WriteLine(ipAddresses[0]); }); block.Post("google.com"); // Post items to the block's ...

jQuery makes handling jSON responses painless, but a bit more work is required when a given request wishes you to send data in JSON format: $.ajax("/json-consuming-route", { data: JSON.stringify({author: {name: "Bullwinkle J. Moose", ...

If you have several objects of monadic types, we can achieve combinations of the values using a 'for comprehension': for { x <- Option(1) y <- Option("b") z <- List(3, 4) } { // Now we can use the x, y, z variables println(x, y, z) x // the last expre...

There are two Dockerfile directives to specify what command to run by default in built images. If you only specify CMD then docker will run that command using the default ENTRYPOINT, which is /bin/sh -c. You can override either or both the entrypoint and/or the command when you start up the built im...

Requirements: 64-bit version of Windows 7 or higher on a machine which supports Hardware Virtualization Technology, and it is enabled. While the docker binary can run natively on Windows, to build and host containers you need to run a Linux virtual machine on the box. 1.12.0 Since version 1.12 y...

Docker is supported on the following 64-bit versions of Ubuntu Linux: Ubuntu Xenial 16.04 (LTS) Ubuntu Wily 15.10 Ubuntu Trusty 14.04 (LTS) Ubuntu Precise 12.04 (LTS) A couple of notes: The following instructions involve installation using Docker packages only, and this ensures obtaining...

The typical way to begin writing webservers in golang is to use the standard library net/http module. There is also a tutorial for it here. The following code also uses it. Here is the simplest possible HTTP server implementation. It responds "Hello World" to any HTTP request. Save the...

HandleFunc registers the handler function for the given pattern in the server mux (router). You can pass define an anonymous function, as we have seen in the basic Hello World example: http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { fmt.Fprintln(w, "Hello, w...

In Go errors can be returned from a function call. The convention is that if a method can fail, the last returned argument is an error. func DoAndReturnSomething() (string, error) { if os.Getenv("ERROR") == "1" { return "", errors.New("The method fai...

The getAll() method retrieves all values from the preferences. We can use it, for instance, to log the current content of the SharedPreferences: private static final String PREFS_FILE = "MyPrefs"; public static void logSharedPreferences(final Context context) { SharedPreferences s...

/// <summary> /// This interface can do Foo /// </summary> public interface ICanDoFoo { // ... } /// <summary> /// This Bar class implements ICanDoFoo interface /// </summary> public class Bar : ICanDoFoo { // ... } Result Interface summary Clas...

Let's take an example of adding a value to a range (as it could be done in a loop for example): 3+1:5 Gives: [1] 4 5 6 7 8 This is because the range operator : has higher precedence than addition operator +. What happens during evaluation is as follows: 3+1:5 3+c(1, 2, 3, 4, 5) expansio...

To show all staged and unstaged changes, use: git diff HEAD NOTE: You can also use the following command: git status -vv The difference being that the output of the latter will actually tell you which changes are staged for commit and which are not.

The built-in mtcars data frame contains information about 32 cars, including their weight, fuel efficiency (in miles-per-gallon), speed, etc. (To find out more about the dataset, use help(mtcars)). If we are interested in the relationship between fuel efficiency (mpg) and weight (wt) we may start p...

Dim array(9) As Integer ' Defines an array variable with 10 Integer elements (0-9). Dim array = New Integer(10) {} ' Defines an array variable with 11 Integer elements (0-10) 'using New. Dim array As Integer() = {1, 2, 3, 4} ' Defines an Integer array variable a...

The <!DOCTYPE> declaration should always be included at the top of the HTML document, before the <html> tag. 5 See HTML 5 Doctype for details on the HTML 5 Doctype. <!DOCTYPE html> 4.01 See HTML 4.01 Doctypes for details on how these types differ from each other. Stri...